The circuit shown is used by the author for switching loads with a total power of about 150 W and is protected with a 1-A fuse. The circuit can easily handle much larger loads however. In that case and/or when using a very inductive load a so-called snubber network is required across the triac. The value of the fuse will also need to be changed as appropriate. The circuit can easily be built into a mains multi-way powerboard. Make sure you have good isolation between the USB and mains sections.
USB Operated Home Appliances Circuit Diagram
Please don't make this circuit if you are not an expert!